Here is a full guide on how to get all achievements in Witch 2 Hell Adventure game.
100% Achievements
For this purpose, you need the 8 keys and have a negative purity.
As the statement indicates for the 2 successes above, nothing difficult
Make the 1st choice when retrieving the keys and wait 30 seconds, with 4 different demons.
Go to the Inquisitor 4 times.
Collect the box in the boss’s room at the cemetery and use the “E” key with an AZERTY keyboard on the 8 bosses and the deadhead.
Same as the Demonslaying succet, but not confronting the deadgead at the end.
For this one I left my game running on its own for 15/20 minutes without touching the control.
For this purpose, you need the 8 keys and have a positive purity. To gain purity it is necessary to save the sister in the library and listen to all the telephone calls.
For this it is necessary to recover the key of the enchanted forest and to go in the cauldron.